With the development of biotechnology, there is an increasing demand for methods and apparatuses for handling a minute object such as a cell sample easily and efficiently.
Up to now, a cell sample is carefully manipulated under a microscope using a manipulation apparatus suitable for operation in a very narrow space between the sample and an object lens. Such manipulation apparatuses are often prepared by users according to the usage. Such manipulation apparatuses are, for example, capillaries and pipettes of specific shapes.
Recently, optical tweezers has become to be used for capturing or moving a very delicate cell sample without damaging cells.
As one of the techniques using such optical tweezers, Japanese Unexamined Patent Publication No. 2000-241310 discloses a technique for capturing a plurality of microorganisms at the same time by using a single optical trapping means in a time-division manner.
Also, Japanese Unexamined Patent Publication No. 2002-219700 discloses a technique to capture and move a minute object by using a surface emitting laser that emits plural laser beams as a light source and by modulating the emission intensity of each light-emitting device spatially and temporally.
As described above, the conventional manipulation method of a minute object such as a cell uses a micromanipulator under a microscope. This manipulation is difficult requiring skill and takes a very long time to achieve desired manipulation. Therefore, it is hard with the conventional method to detect, capture and transfer to a desired position for treatment a minute object such as a cell floating in a liquid for treatment, with ease and speed.
Also, with the method using optical tweezers, generally using single optical tweezers to find and capture a cell sample, it is extremely difficult and takes time to perform such manipulation under a microscope. Even with the methods described in Japanese Unexamined Patent Publication No. 2000-241310 and No. 2002-219700, manipulation is difficult and requires skill.
As described above, effective manipulation of a minute object with the conventional techniques is difficult. Therefore, one of the major obstacles in industrialization in a technical field requiring manipulation of a minute object is low productivity due to the minute object manipulation.
One may consider to improve operability of the method using optical tweezers by arranging the shape of the optical tweezers, or by forming plural optical tweezers at the same time. However, it will require a complicated optical system and a plurality of light sources, raising new problems such as the large size and complication of the apparatus.